This invention relates generally to what is referred to herein as a chipping cutter head usable in removing chips from an elongate region extending along the side of a work piece such as a log, to produce a flat surface along the side of the log bounding the region where wood has been removed in the form of chips. In processing a log, it is common to produce to cut away the convexly curved outer surface regions of a log on opposite sides, to form opposite flat sides in the remainder of the log and chips in the material that is removed.
One type of chipping cutter head which has been proposed in the past is the log slabbing cutter head disclosed in prior issued U.S. Pat. No. 5,271,442. In this cutter head, elongate knives distributed about the cutter head, and extending at an angle so that their cutting edges diverge from the axis of the cutter head progressing outwardly on the cutter head, function to produce cut chips as the cutter head is rotated under power. The cutting edges of these knives converge on each other progressing toward inner ends of the knives, and a flat surface in the log is produced by additional knives, sometimes referred to as planar cutting knives, which move in a common plane extending normal to the axis of the cutter head.
The cutter head of the log slabbing chipper just described, with cutting knives movable in a conical path, has achieved wide commercial acceptance. The cutter heads have been used to produce chips of good quality, with a flat, substantially finished surface bounding the side of the log where wood material has been removed in chip form.
In certain structures, however, the cutter heads offer problems. Further explaining, because of the inclined position of the knives producing the conical cutting action, a cutting head in the region of the outer flared ends of the knives tends to have an excessively large diameter. This tends to introduce cost to the cutter head. Further, the large diameter tends to impart a limit to the rotation speed of the cutter head. With knives extending at an angle, there is a limit to the depth of cut obtainable in a log if a cutter head without a large outer diameter is to be employed. With the depth of cut limited, a problem obviously arises in the handling of tapered or crooked logs.
A general object of this invention is to provide a new and improved chipping cutting head, where the cutter head has a generally cylindrical overall configuration as compared to the general conical configuration in the cutter heads of prior art. Chips are cut from the side of the log which is removed with the cutting edges of knives which extend generally in an axial direction, and without substantial divergence from the axis of the cutter head. A smooth cut surface is produced in the side of the log bounding where the chips have been removed by knife edges that move in a common planar cutting path disposed normal to the rotation axis of the cutting head.
Another object is to provide a chipping cutter head, where the cutting head has a generally cylindrical configuration, and the end of the cutter head as well as the cylindrical outer perimeter of the cutter head are conjointly used for the mounting of knives producing chip removal and a finished cut surface in a log.
A more specific object is to provide a cutter head of generally cylindrical overall configuration, where multiple double-edged removable and replaceable knives are incorporated to provide the cutting edges producing the chips and the flat surface which bounds the log after chip removal. A double-edged knife when mounted on the cutter head has one cutting edge in an exposed operative cutting position, and an opposite cutting edge in an inoperative non-cutting position which is shielded and not exposed. After a period of use, new cutting edges may be provided merely by removing the knives and then replacing them with the knives turned on themselves, so that edges heretofore held in a shielded inoperative position now have an exposed operative cutting position.
Yet a further object of the invention is to provide a chipping cutter head with multiple knives at the end of the cutting head and extending along the cylindrical perimeter thereof, where the body of the cutter head is formed of multiple, disc-shaped body sections, disposed end-to-end. A body section forming one end of the cutter head body mounts one group of knives movable in a circumferential cutting path for removing chips, and another group of knives movable in a planar cutting path for producing a smooth cut surface in the log processed. Body sections disposed away from this end normally need mount only circumferentially located knives usable in the production of chips.